World Food Program report expected to further erode support in Washington for Saudi bombings in Yemen.

The World Food Program and the Food and Agriculture Organization have officially determined that 73,000 Yemeni civilians in rebel-controlled cities are enduring famine conditions, according to two diplomatic sources.

The figures, which appear in a report to be released Thursday, highlight the rapidly deteriorating humanitarian conditions brought about by a four-year-old conflict that has pitted a U.S.-backed Saudi coalition against a Shiite insurgency led by Houthi separatists who receive some support from Iran. While international aid agencies have long warned of severe hunger in Yemen, a full-blown famine will only be declared if 20 percent of the population of any town or district in the country of 28 million experiences severe hunger.

Eight towns and cities, including Hajjah and Taiz, that are controlled by the Houthis have been hardest-hit by what United Nations relief officials believe is the worst humanitarian crisis in the world. But the number fall well short of the 20 percent required for a formal declaration of famine. For instance, more than 32,000 people face famine-like conditions in Hajjah and Taiz, a tiny fraction of the two cities’ combined population of 5.5 million. But more than 3.3 million people there are facing a serious food crisis.

A Saudi-led blockade has transformed Yemen, already the poorest country in the Middle East before the war began, into an economic and humanitarian disaster zone—and fueled the humanitarian crisis.

But the conditions in Houthi towns have been worsened by the separatists’ refusal to permit the distribution of food parcels for children, according to one diplomatic source. Houthis seek to pressure families to bring their starving children to rebel-controlled hospitals, where they receive money from international organizations.

About 2 million children under the age of 5 are severely malnourished in Houthi-controlled areas, and as many as 400,000 children could face starvation if assistance cannot be distributed to them. A recent report from the international aid group Save the Children concluded some 85,000 children have died from starvation since the war began.

Aid organizations say the situation is getting more dire as the war drags on. “Millions are without enough to eat, clean water to drink, and other basics like health care,” said Scott Paul, an expert on Yemen with the humanitarian organization Oxfam America. “Continued fighting continues to claim lives, spread fear, and limit who can afford basic necessities.”

The conflict has also sparked a fierce political debate in Washington over the Trump administration’s relationship with Saudi Arabia, which leads a military coalition in Yemen fighting the Houthi rebels. The coalition has faced criticism for indiscriminately bombing civilian targets, worsening the country’s humanitarian emergency.

A rare alliance of hard-line conservative Republicans and liberal Democrats has advanced a resolution calling for the end to U.S. involvement in the war, which consists of providing arms, intelligence, and logistical support for the Saudi-led coalition. The next vote to advance the resolution, which has important legal implications for the U.S. Congress’s authority over the government’s ability to deploy the military to war zones, could be voted on as soon as Thursday, Senate aides tell Foreign Policy. The Trump administration staunchly opposes the resolution, arguing the United States is not directly involved in the conflict and civilian casualties would be worse without U.S. support. Officials also say it is a key battleground for confronting Iran’s regional sway.

The murder of Jamal Khashoggi, a columnist for theWashington Post and prominent critic of Saudi Crown Prince Mohammed bin Salman, has added scrutiny and anger among lawmakers over the U.S. relationship with Saudi Arabia.

Khashoggi was murdered in the Saudi consulate in Istanbul in October. While CIA assessments leaked to the press say the crown prince is implicated in his murder, U.S. President Donald Trump and his deputies have publicly defended Mohammed bin Salman and U.S. ties with Riyadh. Trump and other senior administration officials condemned Khashoggi’s murder and have announced sanctions against 17 Saudi officials involved in the incident. The list of officials does not include the crown prince.